CONTINUOUS SYNGAS FERMENTATION BY CLOSTRIDIUM LJUNGDAHLII IN A CONTINUOUS STIRRED TANK REACTOR WITH HOLLOW FIBER MEMBRANE

• Main Author: Adisurya Ismail, Guntur
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/42307
• Institution: Institut Teknologi Bandung

Biomass is a renewable resource with high potential as raw material for energy source. One example of biomass utilization is via gasification to produce synthetic gas (syngas) which can be converted to ethanol. Current emerging process is fermenting the syngas which can be done in modest temperature and pressure. There are many factors that can affect the fermentation, and one of them is the operation mode. This thesis presents the result of continuous syngas fermentation by Clostridium ljungdahlii compared to batch fermentation, based on the concentration of the cell, acetate, and ethanol, as well as the syngas utilization rate. Fermentation process is done in two steps. First step is batch fermentation which is done in 10-14 days. The next step is the continuous fermentation. Dilution rate of 0,015 hour-1 and 0,007 hour-1 is used to determine the effect of dilution rate towards the result of the fermentation. Hollow fiber membrane will be used from the second day for media recirculation to improve the gas-liquid transfer rate. Cell concentration is measured using spectrophotometer, ethanol and acetate is measured via HPLC while gas composition in the headspace is determined by using GC. Continuous fermentation with dilution rate of 0,015 hour-1 will produce 2,12 g/L of acetate, 0,09 g/L of ethanol, and 0,56 g/L of biomass. On the other hand, fermentation with dilution rate of 0,007 hour-1 produce 1,05 g/L of acetate, 0,58 g/L of ethanol, and 0,37 g/L of biomass. Increasing the dilution rate will promote the cell growth, but gives opposite effect towards ethanol production which is non-growth associated product. The improvement of cell activities is also proven with the increase in the CO consumption rate which is higher for bigger dilution rate (36% for dilution rate of 0,015 hour-1, compared to 27% for dilution rate of 0,007 hour-1)