New Strategies in Treatment and Enzymatic Processes: Ethanol Production From Sugarcane Bagasse

Introduction

In this study, we investigate the biochemical production of fuel ethanol and other vital commodities biochemicals from lignocellulosic (LC) biomass. In order to produce suitable sugars that may then be fermented to produce ethanol, the majority of large-scale LC ethanol production procedures utilise high solids pre-treatment followed by enzymatic hydrolysis. The pre-treatment and enzymatic hydrolysis processes both have a key role in the overall process economics and energy efficiency during the generation of ethanol. This is due to the fact that efficient pre-treatment techniques get beyond the biomass' refractory nature and offer a substrate that is suitable to the enzyme-based hydrolytic processes. In the aqueous phase, these processes highly solubilize xylose in monomeric, oligomeric, or a combination of the two forms. Enzymatic hydrolysis is performed after high-solid (>15 percent) pilot scale pre-treatment in the DA or SE process. Following pre-treatment, the slurry is typically filtered to produce a liquid phase and a solid phase (lignin and cellulose) (xylose or xylo oligomers). Enzymatic hydrolysis of cellulose to sugars and subsequent fermentation to ethanol are two methods for turning it into alcohol. To obtain adequate yields of sugar and ethanol during enzymatic hydrolysis, solid loading of 5–10% is utilised. In the grand scheme of bioethanol production, each of these procedures calls for more process water, lowering ethanol concentration and requiring more energy for distillation(Chandel et al., 2007).

Lower energy requirements for ethanol distillation arise from greater ethanol concentrations (4-5 w/w%) produced by higher sugar concentrations. Using washed and unwashed sugarcane bagasse, only a small number of experiments have been reported on the various process scenarios for cellulose and hemicellulose hydrolysis. The purpose of the study is to investigate alternative post-treatment techniques to improve bagasse's enzymatic hydrolysis efficiency. This study's major objective is to determine whether washing or other adjustments, like solid-liquid separation and washing, may be eliminated. The streams needed for this investigation came from pilot scale treatments at various combined severity factor (CSF) values, which is dependent on acid dose, temperature, and retention duration. Due to its high acidity, low cost, and well-known effectiveness in the majority of pre-treatments, sulfuric acid is preferred. For the hydrolysis of xylan, oxalic acid is a potent dicarboxylic acid that is largely non-corrosive (Canilha et al., 2010).

Sugarcane bagasse (SB) is a fiber-based agricultural residue left after the juice has been extracted from the sugarcane. SB is considered one of the abundant and low-cost renewable feedstocks for production of biofuels and biochemicals. Biomass biomass (SB) can be converted into sugars for further fermentation to ethanol or biochemicals in a number of ways, such as through the use of hydrolysis and enzymatic processes. Several pre-treatment techniques have been researched in the recent decades for the synthesis of bioethanol and biochemicals from SB. Important characteristics of diluted acid (DA) pre-treatment include a straightforward technique, a short residence period, and inexpensive costs. Pentose and hexose are two monomeric sugars that are produced from lignocellulose with DA treatment. The co-utilization of pentose sugars for the full optimization of biofuel production is made possible by the application of DA. Using cellulase enzymes, the pre-treated solid's cellulose is further degraded into glucose sugars, which are subsequently transformed into electricity. There are several literature studies on the use of a single diluted acid for the conversion of hemicelluloses to their monomeric sugar components, indicating that DA treatment is particularly promising for the generation of bioethanol. The majority of research have used mineral acids such hydrochloric, nitric, sulfuric, and phosphoric acid for the processing of lignocellulosic biomass. Organic acids like maleic and oxalic acids, as well as more expensive alternatives to sulfuric acid, are used in addition to minerals acid (Canilha et al., 2010).