BIOCONVERSION OF LIGNOCELLULOSIC WEEDS TO FUEL ETHANOL BY SHF, SSF AND CBP PROCESSMegh Raj Bhatt, Dr. Rajani Malla, Prof. Dr. Lakshmaiah Sreerama, Ms. Jarina JoshiCentral Department of Biotechnology, Tribhuvan University

ABSTRACT

Lignocellulosic ethanol holds great potential due to the widespread availability, abundance, and relatively low cost of cellulosic materials. However, although the processes are technically feasible, cost-effective processes have been difficult to achieve. Research is needed to let more efficient processing of Lignocellulosic biomass for production to fuel ethanol at lower costs. This research appraises the need for introducing appropriate technology to improve the production of bioethanol, particularly on the community basis and social aspect of sustainability. The effect of fermentation strategies (SHF, SSF and CBP) on ethanol production from six lignocellulosic biomasses (Lantana camara, Saccharum spontaneum, Euphatorium adenophorum, Pinus roxburgi, Eichhornia crassipes and Parthenium hysterophorus) using different pretreatment (0.5M NH4OH and Ganoderma lucidium culture) as well as hydrolysis (0.5M HCl and enzymatic hydrolysis) methods were studied. The quantitative analysis of the dry mass has revealed the maximum cellulosic content of 43% in S. spontaneum and hemicellulosic content of 22% in E. adenophorum. In addition, the parameters for production of cellulase from a newly isolated Trichoderma sps has been optimized to be 28 C of temperature, 72h of incubation time, 4.5 pH ̊� and 1:1 ratio of CMC and cellulose as carbon source. A separate study was taken up to evaluate the role of some fermentation parameters for ethanol production from S. spontaneum by SSF and inoculum size, temperature and incubation time were optimized to be 3% v/v, 30°C and 72 h, respectively. The all three process, SHF, SSF and CBP, showed greatest ethanol yield (0.169, 0.167 and 0.142 g/g of biomass respectively) in S. spontaneum and least in Euphatorium adenophorum i.e. 0.088, 0.143 and 0.072 g/g of biomass via respective processes. The maximum fermentation efficiency of 75% was found while fermenting the fungal pretreated Parthenium hysterophorus via SHF process and minimum efficiency of 31% was found while fermenting the alkali pretreated Lantana camara via CBP. Variability existed among lignocellulosic biomasses for conversion to ethanol after pretreatment, with fungal pretreatment being superior to alkali pretreatment. In addition to types of pretreatment, hydrolysis and fermentation process employed, the results suggested that ethanol yields vary significantly for feedstock by species. More importantly, determinations of xylose, cellulose, fermentable sugars, phenolics and ethanol contents were performed using cheaper, easily accessible and reliable colorimetric and spectrophotometric approaches. Given the results of this study, it offers Bioconversion Of Lignocellulosic Weeds To Fuel Ethanol By SHF, SSF And CBP Process XI a highly feasible and a simple but low-cost process for bioethanol production from various lignocellulosic weeds in developing countries.

Keywords: lignocellulosic biomass, pretreatment, ethanol, bioconversion, fermentation, enzyme hydrolysis