TY - JOUR AU - Ligisan, Aileen R. AU - Tuates Jr., Andres M. PY - 2016/10/18 Y2 - 2024/03/29 TI - Utilization of Onion Solid Waste as Feedstock for Biogas Production JF - Asian Journal of Applied Sciences JA - AJAS VL - 4 IS - 5 SE - Articles DO - UR - https://ajouronline.com/index.php/AJAS/article/view/4117 SP - AB - <p>Utilization of onion solid wastes such as onion leaves and unmarketable onion bulbs as potential feedstock for biogas production was investigated. Response surface methodology (RSM) was used to optimize the interactive effects of temperature, lime concentration and reaction time for the maximum biogas and methane yield, and biodegradation.</p><p>Results showed that the optimum pretreatment conditions established for red creole bulb are:  lime concentration of 4%, temperature of 118<sup>o</sup>C and reaction time of 5 hours; yellow granex bulb – lime concentration of 6.5%, temperature of 102<sup>o</sup>C and reaction time of 2 hours; red creole leaves – lime concentration of 12%, temperature of 118<sup>o</sup>C and reaction time of 6 hours; and yellow granex leaves – lime concentration of 12%, temperature of 118<sup>o</sup>C and reaction time of 5 hours. Red creole bulb produces the highest biogas yield (373.4 ml/g VS and 60.3% CH<sub>4</sub>), followed by yellow granex leaves (366.6 ml/g VS and 58.5% CH<sub>4</sub>), red creole leaves (331ml/g VS and 59.6% CH<sub>4</sub>) and yellow granex bulb (350ml/g VS and 60.7% CH<sub>4</sub>). The regression equation established for biogas yield was found to be adequate for the prediction of independent variables applied. Moreover, the highest and lowest biodegradability of 59.1% and 39% were obtained for Red creole bulb and leaves, respectively. Onion bulb wastes containing easily-degradable substrates had relatively higher methane production potential and biodegradability than onion leaves which have more fiber content. </p> ER -