#TITLE_ALTERNATIVE#

• Main Author: MEILANY (NIM 23006004), DIAH
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/7606
• Institution: Institut Teknologi Bandung

The Indonesian government declared that by 2025, 5% of gasoline will be replaced by bioethanol. Consequently bioethanol industries will produce an enormous quantity of stillage as their wastes. The Anaerobic digestion of stillage will produce volatile organic acids as intermediate products. Volatile organic acids are namely acetic acid, propionic acid and butyric acid. Since acetic acid is the main precursor for methane production, it is very important to determine the best digestion environment for microbes to produce volatile organic acids instead of methane. In this theses, the effect of pH on volatile organic acids was studied.<p> <br /> <br /> <br /> <br /> <br /> Before the stillage was used, it is necesessary to know the characteristics of the stillage. After that it was filtered and dilluted to get COD of about 20 g/L. Then the stillage could be used as a media for microbes acclimation. The anaerobic process proceeded in two kind of bioreactors. A modified erlenmeyer with 1.5 L working volume and a laboratorium scale bioreactor (Biostat) of 7.5 L. In the modified erlenmeyer, the cassava stillage was processed for 72 hours and the pH varied i.e 5, 6 and 7. While in the Bioreactor, pH of 6.5 was used. Samples were taken for eight times in 72 hours fermentation. The temperature was kept constant at 35°C.<p> <br /> <br /> <br /> <br /> <br /> The experiment results showed that the highest concentration of volatile organic acid produced at pH of 7 in the modified erlenmeyer. About 50% of acetic acid and 40% of propionic acid were produced at the end of process. In the modified erlenmeyer, the anaerobic process produced volatile organic acid faster (24 hours) than that of Biostat being 33 hours. A higher propionic acid concentration during the fermentation porcess indicated that the H2 partial pressure in the system was still high.