Mathiyazhakan Kuttiraja

Dilute acid pretreatment and enzymatic saccharification of sugarcane tops for bioethanol production

The aim of this work was to study the feasibility of using sugarcane tops as feedstock for the production of bioethanol. The process involved the pretreatment using acid followed by enzymatic saccharification using cellulases and the process was optimized for various parameters such as biomass loading, enzyme loading, surfactant concentration and incubation time using Box-Behnken design. Under optimum hydrolysis conditions, 0.685 g/g of reducing sugar was produced per gram of pretreated biomass. The fermentation of the hydrolyzate using Saccharomyces cerevisae produced 11.365 g/L of bioethanol with an efficiency of about 50%. This is the first report on utilization of sugarcane tops for bioethanol production.

A novel surfactant-assisted ultrasound pretreatment of sugarcane tops for improved enzymatic release of sugars.

The aim of this study was to develop a novel surfactant-assisted ultrasound pretreatment of sugarcane tops as well as to optimize the effect of various operational parameters on pretreatment and hydrolysis. A novel surfactant-assisted ultrasound pretreatment was developed which could effectively remove hemicelluloses and lignin and improve the reducing sugar yield from sugarcane tops. Operational parameters for pretreatment and hydrolysis were studied and optimized. Under optimal hydrolysis conditions, 0.661 g of reducing sugar was produced per gram of pretreated biomass. The structural changes of native and pretreated biomass were investigated by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared analysis (FTIR). The results indicate that surfactant-assisted ultrasound pretreated sugarcane tops can be used as a potential feed stock for bioethanol production.

Energy requirement for alkali assisted microwave and high pressure reactor pretreatments of cotton plant residue and its hydrolysis for fermentable sugar production for biofuel application.

In the present work, alkali assisted microwave pretreatment (AAMP) of cotton plant residue (CPR) with high pressure reactor pretreatment was compared. Further, modeling of AAMP was attempted. AAMP, followed by enzymatic saccharification was evaluated and the critical parameters were identified to be exposure time, particle size and enzyme loading. The levels of these parameters were optimized using response surface methodology (RSM) to enhance sugar yield. AAMP of CPR (1mm average size) for 6 min at 300 W yielded solid fractions that on hydrolysis resulted in maximum reducing sugar yield of 0.495 g/g. The energy required for AAMP at 300 W for 6 min was 108 kJ whereas high pressure pretreatment (180°C, 100 rpm for 45 min) requires 5 times more energy i.e., 540 kJ. Physiochemical characterization of native and pretreated feedstock revealed differences between high pressure pretreatment and AAMP.

Development of a combined pretreatment and hydrolysis strategy of rice straw for the production of bioethanol and biopolymer.

The present study highlights the development of a combined pretreatment and hydrolysis strategy of rice straw for the production of bioethanol and biopolymer (poly-3-hydroxybutyrate). Maximum reducing sugar yield was 0.374g/g. The hydrolyzate is devoid of major fermentation inhibitors like furfural and organic acids and can be used for fermentation without any detoxification. Fermentation of the non-detoxified hydrolyzate with Saccharomyces cerevisiae yielded 1.48% of ethanol with a fermentation efficiency of 61.25% and with Comamonas sp. yielded 35.86% of poly-3-hydroxybutyrate without any nutrient supplementation. Characterization of native, control as well as the residue left out after combined pretreatment and hydrolysis of RS by scanning electron microscopy and X-ray diffraction showed difference. Compositional analysis revealed that the residue contains lignin and hemicellulose as the major component indicating that major portion of cellulose were hydrolyzed in this strategy.