Examination of different pretreatment and saccharification methods for biobutanol production in SSF process

The objective of this thesis was to examine different pretreatment and saccharification processes of the agriculture residue (i.e. wheat straw) for enhanced production of biobutanol. The purpose was to define the best conditions to obtain maximum sugar yield during the saccharification and butanol yield during the simultaneous saccharification and fermentation (SSF). Three different pretreatment methods for the wheat straws were examined in the present work in comparison with no chemical pretreatment as a reference. This included water, acidic, and alkaline pretreatment. For all cases, physical pretreatment represented by 1 mm size reduction of the straws was applied prior to each pretreatment. Results showed that 16.91 g/L glucose concentration and 100% glucose yield were produced from saccarification with just the physical pretreatment (i.e. no chemical pretreatment). This represented ~5-20% lower sugar release in saccarification compared to the other three pretreatment processes. Saccharification with acid pretreatment obtained the highest sugar concentrations, which were 18.77 g/L glucose and 12.19 g/L xylose. Water pretreatment with SSF was compared with SSF alone (i,e. no chemical pretreatment with SSF). Both processes converted more that 10% of wheat straw into butanol product. This was 2% higher that previous studies. The results illustrated that SSF with no chemical pretreatment obtained 2.61 g/L butanol. Kinetic model was developed for both processes to determine concentration profile of butanol. The SSF with no chemical pretreatment obtained 1.21% root mean square error in comparison with the kinetic model. Similarly, SSF with water pretreatment obtained 1.21% root mean square error in comparison with the kinetic model. Similarly, SSF with water pretreatment obtained 0.83% root mean square error.