Utilization of Rice Straw into Bioethanol through Biological Pathways

The increasing burning of fossil fuels and changes in land use and forestry increase the CO2 in the earth's atmosphere. This condition increases the earth's global temperature, thus causing climate change. In addition, the volume of rice straw waste is very abundant, and the most popular treatment is burning in rice fields. This process also contributes to air pollution and an increase in CO2 gas. Meanwhile, straw is lignocellulosic biomass containing cellulose and hemicellulose as a source of sugar to be converted into bioethanol. Lignocellulosic biomass conversion consists of three main stages, pretreatment, hydrolysis, and fermentation. The process of converting rice straw into bioethanol has been developed. However, the current obstacle is that the conversion process requires high energy, produces chemical waste, and is not environmentally friendly. A biological approach is preferred so that the rice straw conversion process becomes more sustainable. This paper reviews the pretreatment, hydrolysis, and fermentation processes in biologically converting rice straw into bioethanol. Thus it is expected to be able to respond to existing challenges through a biological and more environmentally friendly approach.